<!-- STEP ONE: Paste this code into a new file, save as validation.js  --> 
 
// Generic Form Validation 
// Jacob Hage (jacob@hage.dk) 
var checkObjects	= new Array(); 
var errors		= ""; 
var returnVal		= false; 
var language		= new Array(); 
language["header"]	= "Ocorreram os seguintes erros:\n";
language["start"]	= "."; 
language["field"]	= " O Campo \" "; 
language["require"]	= " \" é necessário "; 
language["min"]		= " e deve conter pelo menos "; 
language["max"]		= " e não deve conter mais do que "; 
language["minmax"]	= " e não mais do que "; 
language["chars"]	= " caracteres"; 
language["num"]		= " e deve conter um numero"; 
language["email"]	= " \" deve conter um endereço de e-mail válido"; 
// ----------------------------------------------------------------------------- 
// define - Call this function in the beginning of the page. I.e. onLoad. 
// n = name of the input field (Required) 
// type= string, num, email (Required) 
// min = the value must have at least [min] characters (Optional) 
// max = the value must have maximum [max] characters (Optional) 
// d = (Optional) 
// ----------------------------------------------------------------------------- 
function define(n, type, HTMLname, min, max, d) { 
 var p; 
 var i; 
 var x; 
 if (!d) d = document; 
 if ((p=n.indexOf("?"))>0&&parent.frames.length) { 
  d = parent.frames[n.substring (p + 1)].document;
  n = n.substring (0, p);
 } 
 if (!(x = d[n]) && d.all) x = d.all[n]; 
 for (i = 0; !x && i < d.forms.length; i++) { 
  x = d.forms[i][n]; 
 } 
for (i = 0; !x && d.layers && i < d.layers.length; i++) {  
  x = define(n, type, HTMLname, min, max, d.layers[i].document); 
  return x;        
 } 
 eval("V_"+n+" = new formResult(x, type, HTMLname, min, max);"); 
 checkObjects[eval(checkObjects.length)] = eval("V_"+n); 
}
 
function formResult(form, type, HTMLname, min, max) { 
 this.form = form; 
 this.type = type; 
 this.HTMLname = HTMLname; 
 this.min  = min; 
 this.max  = max; 
}
 
function validate() { 
 if (checkObjects.length > 0) { 
   errorObject = ""; 
   for (i = 0; i < checkObjects.length; i++) { 
     validateObject = new Object();
     validateObject.form = checkObjects[i].form; 
     validateObject.HTMLname = checkObjects[i].HTMLname; 
     validateObject.val = checkObjects[i].form.value; 
     validateObject.len = checkObjects[i].form.value.length; 
     validateObject.min = checkObjects[i].min; 
     validateObject.max = checkObjects[i].max; 
     validateObject.type = checkObjects[i].type; 
     if (validateObject.type == "num" || validateObject.type == "string") { 
       if ((validateObject.type == "num" && validateObject.len <= 0) || (validateObject.type == "num" && isNaN(validateObject.val))) {
         errors += language['start'] + language['field'] + validateObject.HTMLname + language['require'] + language['num'] + "\n"; 
       } else if (validateObject.min && validateObject.max && (validateObject.len < validateObject.min || validateObject.len > validateObject.max)) { 
         errors += language['start'] + language['field'] + validateObject.HTMLname + language['require'] + language['min'] + validateObject.min + language['minmax'] + validateObject.max+language['chars'] + "\n"; 
       } else if (validateObject.min && !validateObject.max && (validateObject.len < validateObject.min)) {
         errors += language['start'] + language['field'] + validateObject.HTMLname + language['require'] + language['min'] + validateObject.min + language['chars'] + "\n"; 
       } else if (validateObject.max && !validateObject.min &&(validateObject.len > validateObject.max)) { 
         errors += language['start'] + language['field'] + validateObject.HTMLname + language['require'] + language['max'] + validateObject.max + language['chars'] + "\n"; 
       } else if (!validateObject.min && !validateObject.max && validateObject.len <= 0) { 
         errors += language['start'] + language['field'] + validateObject.HTMLname + language['require'] + "\n"; 
       } 
     } else if(validateObject.type == "email") { 
// Checking existense of "@" and ".".  
// Length of must >= 5 and the "." must  
// not directly precede or follow the "@" 
if ((validateObject.val.indexOf("@") == -1) || (validateObject.val.charAt(0) == ".") || (validateObject.val.charAt(0) == "@") || (validateObject.len < 6) || (validateObject.val.indexOf(".") == -1) || (validateObject.val.charAt(validateObject.val.indexOf("@")+1) == ".") || (validateObject.val.charAt(validateObject.val.indexOf("@")-1) == ".")) { 
  errors += language['start'] + language['field'] + validateObject.HTMLname + language['email'] + "\n"; } 
} 
} 
} 
if (errors.length>0) { 
 alert(language["header"].concat("\n" + errors)); 
 errors = ""; 
 returnVal = false; 
} else { 
 returnVal = true; 
} 
}